The present invention relates generally to ground opener units for an agricultural implement and, more particularly, to a down pressure adjustment assembly for setting the amount of down pressure placed on a disc opener unit. The invention is further directed to a down pressure adjustment assembly that may be used to raise and lower a number of disc opener units mounted to a common tool bar.
One type of planting implement is commonly equipped with one or more rows of discs or coulters carried by one or more tool bars, commonly referred to as a disc drill, which is towed by a tractor or other prime mover. Typically, an air cart, which holds seed and/or fertilizer, is also towed by the tractor and pneumatically supplies the individual disc openers with seed and/or fertilizer. The disc openers are attached to the disc drill frame by individualized arms or linkages which allow the disc openers to operate independently of one another. This “independence” allows the discs to independently respond to changes in terrain and field obstructions.
Each disc has a generally flat construction that is rotated a few degrees, e.g., 7 degrees, about a vertical axis so that as the disc is pulled through the soil the leading surface of the disc displaces soil and creates a furrow in the soil. Downward pressure on the disc is provided by a spring or hydraulic cylinder to hold the disc at a desired furrowing depth, e.g., desired seeding depth. The depth at which the disc cuts the furrow into the soil is usually controlled by a gauge wheel that runs in relative close proximity to the disc. In addition to its depth controlling function, for some disc drills, the placement of the gauge wheel close to the disc also assists in keeping the disc surface clean of soil, mud, and other debris buildup. Also, the gauge wheel rides over the soil displaced by the disc as the furrow is being cut to prevent the displaced soil from being thrown.
The disc cuts a furrow or trench in the soil into which seed and/or fertilizer is deposited. The seed and/or fertilizer is dropped through a tube into the trench. The disc holds the trench open on one side and a disc scraper blade holds it open on the opposite side. The trench walls then collapse onto the seed and/or fertilizer when the disc and scraper blade pass. A trailing wheel then packs the soil atop the seed and/or fertilizer. Most disc drills include a spring that is used to adjust the amount of packing pressure applied by the trailing (packer) wheel.
A conventional disc drill will include a lift assembly for lifting and lowering the disc opener unit. These lift assemblies may also be used to set a downward pressure on the disc opener units. For disc opener units that are not coupled to the tool bar with a parallel linkage, it is possible for the disc opener unit to tip up or tip down as the down pressure is adjusted.